The radio horizon is the locus of points at which direct rays from an antenna are tangential to the surface of the Earth.
Long Distance Propagation of HF Radio Waves
If the Earth were a perfect sphere without an atmosphere, the radio horizon would be a circle. The radio horizon of the transmitting and receiving antennas can be added together to increase the effective communication range. Radio wave propagation is affected by atmospheric conditions, ionospheric absorption , and the presence of obstructions, for example mountains or trees.
Simple formulas that include the effect of the atmosphere give the range as:. The simple formulas give a best-case approximation of the maximum propagation distance, but are not sufficient to estimate the quality of service at any location. Earth bulge is a term used in telecommunications. It refers to the circular segment of earth profile that blocks off long distance communications.
Since the geometric line of sight passes at varying heights over the Earth, the propagating radio wave encounters slightly different propagation conditions over the path. Assuming a perfect sphere with no terrain irregularity, the distance to the horizon from a high altitude transmitter i.
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Let R be the radius of the Earth and h be the altitude of a telecommunication station. The line of sight distance d of this station is given by the Pythagorean theorem ;. If the height is given in metres, and distance in kilometres, .
The above analysis does not consider the effect of atmosphere on the propagation path of RF signals. Thus, the maximum service range of the station is not equal to the line of sight geometric distance. Usually, a factor k is used in the equation above, modified to be. But in stormy weather, k may decrease to cause fading in transmission. That is equivalent to a hypothetical decrease in Earth radius and an increase of Earth bulge.
[PDF Download] Essentials of Radio Wave Propagation (The Cambridge Wireless Essentials Series)
In normal weather conditions, the service range of a station at an altitude of m with respect to receivers at sea level can be found as,. From Wikipedia, the free encyclopedia.
For other uses, see Line-of-sight disambiguation. See also: Radar horizon. R is the radius of the Earth, h is the height of the transmitter exaggerated , d is the line of sight distance. Radio portal. Cambridge University Press. Technical Monograph Brussels: European Broadcasting Union.
In microwave radio link chains, both stations are at high altitudes. Applications, including point-to-point radio links, broadcasting and earth-space communications, are thoroughly treated, and more sophisticated methods, which form the basis of software tools for both network planning and spectrum management, are also described. For a rapid understanding and insight into radio propagation, sufficient to enable you to undertake real-world engineering tasks, this concise book is invaluable for network planners, hardware designers, spectrum managers, senior technical managers and policy makers who are either new to radio propagation or who need a quick reference guide.
The effect of obstacles. Estimating the received signal strength in complex. Atmospheric effects. System design and interference management.
Essentials of Radio Wave Propagation by Christopher Haslett - PDF Drive
Softwarebased tools. Phasor arithmetic and phasor diagrams. Explanation of the link budget.